That's actually a good question already pointed out in mauricemach/zappa#99 and I honestly have no proper answer, although I suspect this might be have been related to setting databag to this, in which case the context should be the databag -- but that code never made it into helpers, and the original commit that added this didn't have a justification for it so I don't know what the scenario would be.

My proposal is to:

remove the extraneous argument from helpers;

get rid of databag == "this" to ensure that the context is always @.

(Since I was the one who asked for databag == "this" but never used it, I suspect there isn't much usage around.)

We can keep databag (or introduce a new setting, maybe params?) as a boolean, to replace databag == "param". (This indicates that the databag should be passed as argument to handlers. There's a performance penalty in doing so, so I don't want to make it the default though.)